/Engine/Source/Runtime/InteractiveToolsFramework/Public/BaseGizmos/ParameterToTransformAdapters.h
Optional position constraint function. Called during interaction with the new transform origin. To snap the transform to a new position, return as second value, and return true from your lambda. Note that returned snap point will be projected onto the current translation origin/axis.
true if constraint point was found and should be used, false to ignore
virtual float GetParameter() const